Studies of the role of thiol-disulfide reactions of proteins in physiologically important regulatory processes are proposed and justified on the basis of chemical, biochemical, and biological considerations. Initial studies with the fungus Neurospora crassa show that high oxidized glutathione (GSSG) and protein bound glutathione (PSSG) levels occur in the dormant spores (conidia) relative to the vegetative state (mycelia) and that these differences largely disappear in the first minutes of the conidial germination process which connects these two states. It is proposed that high disulfide levels are important in controlling the properties associated with dormancy and studies to test and elaborate this hypothesis in fungi, bacteria, seeds and other systems with dormant states are proposed. These include: (1) a test of the generality of the finding of N. crassa by determination of GSSG and PSSG levels in the dormant or quiessant states and in the active states of five other organisms (Dictyosteleum discoideum, Bacillus subtilis, wheat embryo, sea urchin, Artemia salina); (2) an essentialy complete elaboration of the protein SH/SS differences between conidia and mycelia of N. crassa; (3) elucidation of the separate roles of hydration state and disulfide content in determining the thermo- resistance of N. crassa conidia; (4) studies of the role of SH/SS phenomenon in the control of enzyme activities of N. crassa; (5) purification of glutathione reductase from N. crassa and studies of natural and synthetic inhibitors of this enzyme. The results of these studies may have important consequences for our understanding of the mechanism by which protein synthesis and other enzymatic processes are regulated in dormant states and activated when dormancy is broken. They may provide the basis for the development of improved sterilization methods and antibiotics for use against infectious diseases.